PHYSICAL HISTORY OF THE AMAZONS. 399 
* 
existed at all, it must have been cosmic ; and it is quite 
as rational to look for its traces in the Western as in the 
Eastern hemisphere, to the south of the equator as to the 
north of it. Impressed by this wider view of the subject, 
confirmed by a number of unpublished investigations 
which I have made during the last three or four years 
in the United States, I came to South America, expect- 
ing to find in the tropical regions new evidences of a 
bygone glacial period, though, of course, under different 
aspects. " Such a result seemed to me the logical se- 
quence of what I had already observed in Europe and in 
North America. 
On my arrival in Rio de Janeiro, - - the port at which 
I first landed in Brazil, my attention was immediately 
attracted by a very peculiar formation consisting of an 
ochraceous, highly ferruginous, sandy clay. During a stay of 
three months in Rio, whence I made many excursions into 
the neighboring country, I had opportunities of studying 
this deposit, both in the province of Rio de Janeiro and in 
the adjoining province of Minas Geraes. I found that it 
rested everywhere upon the undulating surfaces of the 
solid rocks in place, was almost entirely destitute of strat- 
ification, and contained a variety of pebbles and boul- 
ders. The pebbles were chiefly quartz, sometimes scat- 
tered indiscriminately throughout the deposit, sometimes 
lying in a seam between it and the rock below ; while 
the boulders were either sunk in its mass, or resting loose- 
ly on the surface. At Tijuca, a few miles out of the city 
of Rio, among the picturesque hills lying to the south- 
west of it, these phenomena may be seen in great per- 
fection. Near Bennett's Hotel there are a great num- 
ber of erratic boulders, having no connection whatever 
